Terpenes are ubiquitous starting materials for synthesizing fragrance ingredients. Saturated, tertiary terpene alcohols, which derive from turpentines and incorporate 2-methylbutane moieties, are important fragrance ingredients or intermediates because of their availability and relatively low cost. These alcohols include trans-pinanol, cis-pinanol, dihydroplinol, tetrahydromyrcenol, tetrahydrolinalool, and other valuable compounds. Cis-pinanol, for example, is commonly pyrolyzed to make industrial quantities of linalool.
Oxidation of trans-pinanol with mercury(II) oxide and bromine or with lead tetraacetate and iodine provides 6,9-dimethyl-7-oxatricyclo[4.3.0.03,9]nonane, compound 1, a valuable intermediate for synthesizing more complex terpene derivatives (see, e.g., U.S. Pat. Nos. 3,481,998 and 3,658,851; Tetrahedron Lett. (1967) 905; J. Am. Chem. Soc. 97 (1969) 4771 and 98 (1976) 4594; and J. Chem. Soc., Perkin Trans. I (1972) 943). More recently, cyclic ether 1 has also been made by dehydrating trans-pinane hydroperoxide with a mixture of iron(II) and copper(II) sulfates (Chem. Lett. (2002) 830), as shown below. While the methods are effective, a preferred one would avoid the need to make a hydroperoxide intermediate or to use toxic lead or mercury reagents.

A number of cyclobutanes have been identified as valuable fragrance components. Unfortunately, synthesizing cyclobutanes is usually far from trivial, particularly if the starting materials are limited to readily available, inexpensive mixtures such as terpenes. Despite the challenges, cyclobutanes such as pinonyl alcohol, pinonic acid, and esters of pinonic acid have been reported (see U.S. Pat. Nos. 2,824,138, 3,030,337, 3,361,820, and 4,048,120). Surprisingly little progress has been made during the past thirty years to develop new terpene-based routes to cyclobutanes.